George Fletcher and Jens Ohlin’s book, DEFENDING HUMANITY, presents a remarkable tour through the theoretical, historical, and cultural justifications for the use of force by one country against another. Drawing from sources as disparate as the Bible, contemporary philosophy, UN documentary history, and the domestic law of self defense, the authors present a case for why the international community should embrace the concept of “légitime defense,” namely that countries may use force both to defend other countries as well as to protect groups threatened within those other countries. The French antecedents of légitime defense support an understanding of self defense richer than our own more narrow conception of collective defense as under NATO. Although many will dispute the central arguments, all readers will benefit from grappling with their account, and all should enjoy the lively prose.

At the core, Fletcher and Ohlin assert three propositions central to the study of the use of force internationally today. First, they argue that governments may not only use force to repel overt attacks on their soil, but also may launch preemptive attacks. They caution, however, that the legitimacy of such attacks hinges on whether the threat of force is imminent, and note that the broader the concept of imminence, the less the need to define an attack as “preemptive” rather than defensive. They articulate no precise lines but suggest that imminence “must be something broader than troops crossing the border, but something narrower than mere preparations for war such as strategic planning” (p.159). As they do throughout the book, they rely on principles of self defense in domestic law in reaching their conclusions. In the domestic context, they note, there is no such thing as “preemptive” self-defense – either the threatened use of force was imminent or not. They continue that the debate over the propriety of preventive or preemptive war should be refocused on a more contextualized understanding of imminence.

In the wake of the United States’ invasion of Iraq, the authors (p.162) join others who have condemned President Bush’s policies as precipitous. To them, the domestic analogy holds: Individuals cannot take vengeance on aggressors when the threat of serious bodily harm is not imminent. Taking a life when the aggressor is sleeping is almost never justified, no matter how heinous the aggressor’s behavior while awake. Our understanding of women who kill their abusers is consistent with this paradigm because, to be eligible for self-defense, defendants must show that they reasonably believed that their abusers would imminently inflict serious bodily injury. In the international arena, [*934] Israel’s bombing of the Osirak reactor in 1981 similarly cannot be justified as defensive or “preemptive” because Iraq’s nuclear plans were at too early a stage. Fletcher and Ohlin add (pp.96-102) that any preemptive attack must also be proportionate. Argentina’s foray into the Falklands would not have justified a wide-ranging attack by Great Britain on Argentina itself.

Second, the authors argue that countries have the right to come to the defense of others. The underlying premise of NATO, in other words, is entirely consistent with their thesis. Fletcher and Ohlin persuasively argue further that the rationale for defense of others is not limited to treaties or other alliances. All sovereign countries enjoy the right to a continued existence, and thus every country legitimately could have come to Kuwait’s defense when Saddam Hussein’s armies invaded, irrespective of a treaty or formal request for help. The French tradition of légitime defense helps bolster their position, despite what some have argued is a narrower view in the UN Charter. Indeed, their novel retelling of the drafting history is informative. Similarly, under the United States’ Model Penal Code (MPC), adopted widely by the states (at least in part), individuals are justified in taking a life when coming to the aid of others who face an imminent risk of death or serious bodily harm. The domestic analogy helps gird the authors’ position.

In what might be the most provocative and innovative part of the book, Fletcher and Ohlin extend their analysis to the use of force for humanitarian purposes. Countries have the right to use force not only to help other governments that have been attacked or face imminent attack, but also to extend aid to what they term “nations” within other countries. “Nations” in their terminology, as opposed to the more cabined notion of internationally recognized states, refer to groups of peoples defined by ethnicity, religion, and/or culture. Although the authors recognize (p.138) that such peoples may lack legal personalities under international law, they are not without protection. The right of self defense, they argue (p.146), extends to all peoples or nations, and thus the right to defend others includes not just states but peoples or nations attacked within. For instance, the United States was justified, they argue (p.152), in coming to Kosovo’s aid because Albanian Kosovars constituted a distinct nation within Serbia who were at risk of annihilation. The same might be true of Kurds in Iraq during the Saddam Hussein massacres of the early 1990s.

Not all of the authors’ exegesis is seamless. For instance, they initially reject the relevance to an international system of “excuses” (as opposed to justifications) for the use of force, by which they mean the exercise of force which, while not condoned, can be pardoned by the international community. In domestic law, excuses comprise a category including some forms of duress, insanity, and necessity, which can at times either exonerate or mitigate punishment. In the international arena, what if countries are compelled by others to use force, or what if they invade another because of widespread starvation at home? Fletcher and Ohlin suggest (pp.47, 58) early in the book that there is no room for “excuse” in international law. Their rejection of such excuses arguably rests on the insight that, while domestic law [*935] and the MPC focuses on blameworthiness and punishment, the international order rather needs “to be able to make well defined charges of aggression and to respond with well-grounded claims of justification” (p.48). Countries use force, whether offensively or defensively, at the risk that the international community ex post will view their conduct as illegitimate. The authors urge that international law cannot brook legitimating acts of war by two parties at once. If the use of force is justified by Country A, then Country B cannot legitimately counter that force. In other words, Country B’s use of force to repel the attack neither can be justified nor excused in the eyes of the international community.

Later in the book, however (p.178), Fletcher and Ohlin suggest that the salience of reasonable mistake in international law, which they and others have likened to an “excuse,” should be further studied. Countries may not only misperceive when an attack is imminent, but they also may err in determining when defense of others is legitimate. For instance, should the United States escape censure or other sanctions internationally for its apparent mistake that there were weapons of mass destruction in Iraq and that the prospect of their use was imminent? Although they hedge, the authors apparently are of the view that, as long as the mistake is reasonable and based on publicly acknowledged data, a mistake should excuse the invasion even if otherwise unjustified under international law. Fletcher and Ohlin’s acknowledgment that a “reasonable mistake” may exonerate a country is difficult to reconcile with their earlier goal of achieving an international system that plainly demarcates legitimate from illegitimate behavior. They do not try to resolve the tension between the earlier argument (pp.47-48) that “strong” rights of self-defense are needed in the international arena with the subsequent recognition of a special role for “reasonable mistake.”

Moreover, the authors’ effort to expand the international understanding of self defense to include intervention to defend “nations” subject to persecution in other states enhances the likelihood of ex post second-guessing even more than their allowance of a “reasonable mistake.” Although Fletcher and Ohlin are sympathetic to the United States’ defense of Kosovo, they might not be as sympathetic to Russia’s more recent use of force ostensibly to protect individuals in South Ossetia. Arguably, residents of South Ossetia fall within the authors’ definition of “nations.” Perhaps the South Ossetians were justified in rejecting the rule of Georgians, but perhaps they constitute merely a minority that has failed to achieve its political goals through the ballot box and then unjustifiably resorted to violence. There is no accepted metric to assess when force is justified to protect “nations” within countries, whether the Uigurs in China or the Kurds in Turkey. The authors’ argument that force can be deployed to defend humanity thus makes the goal of “well defined charges of aggression” that much harder to attain. The more subjective the contexts in which the use of force is justifiable (or excused), the more difficult it is to police international behavior. Given the widely divergent views on whether the use of force for humanitarian purposes is legitimate in Darfur, Georgia, or Tibet, it is not likely that a consensus can be [*936] attained to distinguish between aggression and legitimate defense on humanitarian grounds.